1. Field of the Invention
This invention relates to a bandwidth control server, a bandwidth control program recorded on a computer readable record medium, and a monitoring system and, more particularly, to a bandwidth control server and a bandwidth control program recorded on a computer readable record medium which are connected to a plurality of cameras via a network for controlling the sending of camera image data according to a bandwidth of the network, and a monitoring system for acquiring image data obtained by a plurality of cameras and for performing centralized monitoring of a situation.
2. Description of the Related Art
A monitoring system for receiving image data obtained by a plurality of cameras installed at a remote place (for example, by a river) via a network and for performing centralized monitoring of a situation at the remote place is known. If a failure occurs in a main line usually used in such a monitoring system, then switching from the main line to a subline is performed to transfer image data.
However, when switching from a wide-band main line to a narrow-band subline is performed to send or receive image data, all camera image data cannot be sent or received because of bandwidth limitation. If a network bandwidth is limited in this way, the following problem arises. If it is necessary to immediately acquire, for example, information regarding damage caused in an area where a disaster has occurred, it is possible that such information cannot be received. Accordingly, an image bypass control server for permitting the sending of image data in descending order of priority on the basis of priority assigned in advance to each camera in the case of the occurrence of a failure in a main line is proposed (see, for example, Japanese Patent Laid-Open Publication No. 2005-184387 (FIG. 1)). In addition, when notice of a disaster is sent from a camera, this image bypass control server performs switching in order to preferentially acquire image data from the camera from which the notice of a disaster is sent.
With the conventional image bypass control, however, it is difficult to make each camera send image data in accordance with priority corresponding to a situation at each moment.
Camera priority at the time of the occurrence of a disaster is not always fixed and changes according to the type of the disaster. For example, if a heavy rain warning is issued, then the priority of an image obtained by a camera used for taking the upper waters of a river should be raised in order to monitor the conditions of a landslide or a flood. On the other hand, if a tidal wave warning is issued, then the priority of an image obtained by a camera used for taking a coastline should be raised in order to monitor the conditions of the coastline. Priority changes in this way according to a situation at each moment. If priority is fixed, it is impossible to flexibly acquire image data according to a change in conditions. As a result, it is possible that image data for a point that is the most important at that point of time cannot be obtained automatically.
In addition, a camera which detects a disaster and which sends notice of the disaster sends image data preferentially. However, a bandwidth is assigned in accordance with fixed priority until the notice of the disaster is received. Accordingly, even if a sign is detected before the occurrence of the disaster and a warning is issued, it is impossible to comply with a request to monitor conditions in an area over which the warning is issued. In such a case, manual switching must be performed. This is inconvenient.